- ID:
- ivo://CDS.VizieR/J/AJ/136/1067
- Title:
- New beta Lyrae and Algol candidates in NSVS
- Short Name:
- J/AJ/136/1067
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have classified 409 objects in the Northern Sky Variability Survey (NSVS) as new beta Lyrae or Algol-type eclipsing binaries. These candidates have outside of eclipse magnitudes of ~10-13. Through automated Fourier analysis routines and some manual inspection, we list the period, eclipse depths, coordinates, an estimate of the time of primary eclipse, and the 2MASS colors for these candidates. This list of new beta Lyrae type candidates greatly increases the number of known systems of this type. We have also identified 37 candidate low-mass, main-sequence pairs (M_1,2_<1M_{sun}_,T<5500K) in the NSVS database. If confirmed, these systems will greatly increase the number of such low-mass systems known as well as help constrain atmospheric models for these types of stars.
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- ID:
- ivo://CDS.VizieR/J/AJ/150/27
- Title:
- New catalog of variable stars in M37 field
- Short Name:
- J/AJ/150/27
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a comprehensive re-analysis of stellar photometric variability in the field of the open cluster M37 following the application of a new photometry and de-trending method to the MMT/Megacam image archive. This new analysis allows a rare opportunity to explore photometric variability over a broad range of timescales, from minutes to a month. The intent of this work is to examine the entire sample of more than 30000 objects for periodic, aperiodic, and sporadic behaviors in their light curves. We show a modified version of the fast {chi}^2^ periodogram algorithm (F{chi}^2^) and change-point analysis as tools for detecting and assessing the significance of periodic and non-periodic variations. The benefits of our new photometry and analysis methods are evident. A total of 2306 stars exhibit convincing variations that are induced by flares, pulsations, eclipses, starspots, and unknown causes in some cases. This represents a 60% increase in the number of variables known in this field. Moreover, 30 of the previously identified variables are found to be false positives resulting from time-dependent systematic effects. The new catalog includes 61 eclipsing binary systems, 92 multiperiodic variable stars, 132 aperiodic variables, and 436 flare stars, as well as several hundreds of rotating variables. Based on extended and improved catalog of variables, we investigate the basic properties (e.g., period, amplitude, type) of all variables. The catalog can be accessed through the web interface (http://stardb.yonsei.ac.kr/).
- ID:
- ivo://CDS.VizieR/J/A+A/619/A85
- Title:
- 54 new eccentric galactic eclipsing binaries
- Short Name:
- J/A+A/619/A85
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an analysis of the apsidal motion and light curve parameters of 54 never-before-studied galactic Algol-type binaries. This is the first analysis of such a large sample of eccentric eclipsing binaries in our Galaxy, and has enabled us to identify several systems that are worthy of further study. Bringing together data from various databases and surveys, supplemented with new observations, we have been able to trace the long-term evolution of the eccentric orbit over durations extending back up to several decades. Our present study explores a rather different sample of stars to those presented in the previously published catalogue of eccentric eclipsing binaries, sampling to fainter magnitudes, covering later spectral types, sensitive to different orbital periods with more than 50% of our systems having periods longer than six days. The typical apsidal motion in the sample is rather slow (mostly of order of centuries long), although in some cases this is less than 50yr. All of the systems, except one, have eccentricities less than 0.5, with an average value of 0.23. Several of the stars also show evidence for additional period variability. In particular we can identify three systems in the sample, HD 44093, V611 Pup, and HD 313631, which likely represent relativistic apsidal rotators.
- ID:
- ivo://CDS.VizieR/J/other/IBVS/5586
- Title:
- New elements for 80 eclipsing binaries V.
- Short Name:
- J/other/IBVS/558
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This research presents new elements for 80 eclipsing binaries found with the help of the ASAS-3 (Cat. <II/264>), Hipparcos (Cat. <I/239>) and NSVS (2004AJ....127.2436W) databases.
- ID:
- ivo://CDS.VizieR/J/PASP/131/G5001
- Title:
- New variable stars and eclipsing binaries
- Short Name:
- J/PASP/131/G5001
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Evryscope is a telescope array designed to open a new parameter space in optical astronomy, detecting short-timescale events across extremely large sky areas simultaneously. The system consists of a 780 MPix 22-camera array with an 8150 sq. deg. field of view, 13'' per pixel sampling, and the ability to detect objects down to m_g'_~=16 in each 2-minute dark-sky exposure. The Evryscope, covering 18400 sq. deg. with hours of high-cadence exposure time each night, is designed to find the rare events that require all-sky monitoring, including transiting exoplanets around exotic stars like white dwarfs and hot subdwarfs, stellar activity of all types within our galaxy, nearby supernovae, and other transient events such as gamma-ray bursts and gravitational-wave electromagnetic counterparts. The system averages 5000 images per night with ~300000 sources per image, and to date has taken over 3.0M images, totaling 250 TB of raw data. The resulting light curve database has light curves for 9.3M targets, averaging 32600 epochs per target through 2018. This paper summarizes the hardware and performance of the Evryscope, including the lessons learned during telescope design, electronics design, a procedure for the precision polar alignment of mounts for Evryscope-like systems, robotic control and operations, and safety and performance-optimization systems. We measure the on-sky performance of the Evryscope, discuss its data analysis pipelines, and present some example variable star and eclipsing binary discoveries from the telescope. We also discuss new discoveries of very rare objects including two hot subdwarf eclipsing binaries with late M-dwarf secondaries (HW Vir systems), two white dwarf/hot subdwarf short-period binaries, and four hot subdwarf reflection binaries. We conclude with the status of our transit surveys, M-dwarf flare survey, and transient detection.
- ID:
- ivo://CDS.VizieR/J/A+A/519/A12
- Title:
- 1318 new variable stars in Galactic plane
- Short Name:
- J/A+A/519/A12
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have conducted a deep photometric survey of a 0.5deg*0.5deg area of the Galactic Plane using the WFI instrument on the 2.2-m ESO telescope on La Silla, Chile. The dataset comprises a total of 267 R-band images, 204 from a 16 day observation run in 2005, supplemented by 63 images from a six week period in 2002. Our reduction employed the new numerical kernel difference image analysis method as implemented in the pySIS3 code and resulted in more than 500000 lightcurves of stars down to a magnitude limit of R~24.5. A search for variable stars resulted in the detection of 1318 variables of different types. 1011 of these are eclipsing or contact binary stars. A number of the contact binaries have low mass-ratios and several of the detached binaries appear to have low-mass components. Three candidate contact binaries have periods at the known cut off including two with periods lower than any previously published. Also identified are 3 possible pre-main sequence detached eclipsing binaries.
- ID:
- ivo://CDS.VizieR/J/MNRAS/482/3058
- Title:
- New variable stars towards Galactic Bulge
- Short Name:
- J/MNRAS/482/3058
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the detection of 3714 variable stars towards the Galactic bulge, including 2521 previously uncatalogued variables, using time-series photometry extracted from data obtained with the VIMOS imager at the Very Large Telescope. Observations of the Sagittarius Window Eclipsing Extrasolar Planet Search (SWEEPS) field in the Galactic Bulge were taken over 2yr between March and October at a cadence of ~4d, enabling the detection of variables with periods up to ~100d. Many of these were already known, but we detected a significant number of new variables, including 11 Cepheids, a further 88 potential Cepheid candidates, and many contact binaries. Here we publish the catalogue of the new variables, containing coordinates, mean magnitudes as well as periods and classification; full light curves for these variables are also made available electronically.
- ID:
- ivo://CDS.VizieR/J/AJ/155/177
- Title:
- Obliquities of planetary & eclipsing binary systems
- Short Name:
- J/AJ/155/177
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The light curve of an eclipsing system shows anomalies whenever the eclipsing body passes in front of active regions on the eclipsed star. In some cases, the pattern of anomalies can be used to determine the obliquity {Psi} of the eclipsed star. Here we present a method for detecting and analyzing these patterns, based on a statistical test for correlations between the anomalies observed in a sequence of eclipses. Compared to previous methods, ours makes fewer assumptions and is easier to automate. We apply it to a sample of 64 stars with transiting planets and 24 eclipsing binaries for which precise space-based data are available, and for which there was either some indication of flux anomalies or a previously reported obliquity measurement. We were able to determine obliquities for 10 stars with hot Jupiters. In particular we found {Psi}~<10{deg} for Kepler-45, which is only the second M dwarf with a measured obliquity. The other eight cases are G and K stars with low obliquities. Among the eclipsing binaries, we were able to determine obliquities in eight cases, all of which are consistent with zero. Our results also reveal some common patterns of stellar activity for magnetically active G and K stars, including persistently active longitudes.
- ID:
- ivo://CDS.VizieR/J/MNRAS/448/2890
- Title:
- Observation of six NSVS eclipsing binaries
- Short Name:
- J/MNRAS/448/2890
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We carried out photometric and low-resolution spectral observations of six eclipsing ultrashort-period binaries with main-sequence (MS)components. The light-curve solutions of the Rozhen observations show that all targets are overcontact systems. We found a well-defined empirical relation between period and semi-major axis for the short-period binaries and used it for estimation of the global parameters of the targets. Our results revealed that NSVS 925605 is quite an interesting target: (i) it is one of a few contact binaries with M components; (ii) it exhibits high activity (emission in the H{alpha} line, X-ray emission, large cool spots, non-Planck energy distribution); (iii) its components differ in temperature by 700 K. All the appearances of high magnetic activity and the huge fill-out factor (0.7) of NSVS 925605 may be a precursor of the predicted merging of close magnetic binaries. Another unusual binary is NSVS 2700153, which reveals considerable long-term variability.
- ID:
- ivo://CDS.VizieR/J/AJ/134/2353
- Title:
- Observations of contact binaries
- Short Name:
- J/AJ/134/2353
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results of the Canada-France-Hawaii Telescope adaptive optics (AO) search for companions of a homogeneous group of contact binary stars, as a contribution to our attempts to prove the hypothesis that these binaries require a third star to become as close as observed.
